Centrifuge tube adapter

ABSTRACT

A centrifuge tube adapter for supporting a closed tube in a cavity of a vertical angle centrifuge rotor includes an inboard and an outboard adapter segment. A hinge connects the segments and supports relative pivotal movement of one segment with respect to the other. The hinge comprises a pair of axles formed at the lower end of one segment and a pair of trunnions formed at a corresponding location on the other segment. The inboard segment has a flange and the outboard segment has a channel therein sized to receive the flange. The flange has serrations thereon.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.07/695,871, filed May 6, 1991, now abandoned, which is itself acontinuation-in-part of application Ser. No. 07/552,631, filed Jul. 13,1990, now abandoned, which is itself a continuation-in-part ofapplication Ser. No. 07/432,646, filed Nov. 7, 1989, now abandoned, allin the names of Romanauskas and Sheeran and all assigned to the assigneeof the present invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an adapter for holding a centrifugetube in a centrifuge rotor cavity, and in particular, to an adapterhaving two segments, the segments being in some cases joined by a hinge,the hinge axis extending perpendicular to the axis of the adapter.

2. Description of the Prior Art

In the operation of a centrifuge it is important that the size and shapeof the tube in which a liquid sample is carried closely conforms to thesize and shape of the cavity in the centrifuge rotor in which the tubeis received. During centrifugation the centrifugal force exerted on thetube itself and the liquid therein acts to deform the centrifuge tube. Acentrifuge tube which does not closely conform to the rotor cavity maythus be deformed to the point of rupture. Even if the tube does notrupture the deformation may make the tube difficult to remove from therotor cavity. Moreover, even if the deformed tube is removable from therotor, the return of the tube to its undeformed shape may agitate thecontents of the tube to an extent that destroys the sample separation.

When the shape and size of a centrifuge tube does not closely conform tothe shape and size of the rotor cavity in which it is to be disposed adevice known as a tube adapter is usually employed. The tube adapter hasan interior cavity having a shape and size which closely conforms to theshape and size of the centrifuge tube being adapted. The exterior shapeand size of the adapter closely conforms to the shape and size of therotor cavity in which the tube is to be used. The adapter serves tosupport a tube within the cavity in which it is received and thus servesto prevent deformation of the tube during centrifugation.

Exemplary of an adapter formed of a single unitary member is the devicedisclosed in U.S. Pat. No. 4,304,356 (Chulay et al.). This adaptersupports only the neck region of the centrifuge tube and is fabricatedof a material having a lower density than the liquid being carriedtherein to prevent bottoming of the adapter in the rotor cavity in theevent of tube rupture.

Exemplary of an adapter formed of two piece construction is the deviceshown in U.S. Pat. No. 3,674,197 (Mitchell et al.), assigned to theassignee hereof. This adapter comprises two discrete segments, each ofwhich has an indentation therein. When joined the indentations form arecess for receiving a collapsible bag during centrifugation. Theadapter disclosed in this patent includes aperture(s) through whichtubes from the bag exit the adapter. Thus, the possibility exists thatthe bag may extrude through these apertures if the adapter were toundergo centrifugation in a vertical angle rotor.

An adapter arrangement formed of two discrete adapter segments anduseful to support the capped end of a centrifuge tube is available aspart of the Nalgene Ultra-Lok Tube System sold by Fisher ScientificIncorporated.

U.S. Pat. No. 4,692,137 (Anthony) discloses a tube adapter having twosegments which are hinged along the lateral edges of the segments. Thehinge axes align in parallel relationship to the axis of the cavity inwhich the adapter is received. The disposition of hinges along thelateral edges of the segments is believed disadvantageous in that such adisposition may interfere with the insertion or removal of the adapterinto or from the rotor cavity.

U.S. Pat. No. 3,998,383 (Romanauskas et al.) and U.S. Pat. No. 4,015,775(Rohde), both assigned to the assignee of the present invention,disclose centrifuge rotors of the vertical angle type. In such a rotorthe axis of the rotor cavities is substantially parallel to the axis ofrotation. When using a vertical angle rotor it is necessary that a capbe provided at the mouth of each cavity to impose a vertical restrainingforce on the tube disposed in the cavity. Even though the tube may bedisposed in an adapter received within the cavity, without such acapping arrangement the possibility exists that the pressure of theliquid during centrifugation may rupture the tube. U.S. Pat. No.3,998,383 (Romanauskas et al.) exemplifies a typical capping arrangementfor a vertical angle rotor.

Such capping arrangements must be individually threaded into the rotorbody. Moreover, in order to provide proper support it is necessary thatthe capping arrangement be in intimate contact with the tube. Improperassembly can thus lead to the possibility of tube rupture and/or capfailure. For these reasons such capping arrangements are believeddisadvantageous.

In view of the foregoing it is believed advantageous to provide anadapter for use in a vertical angle rotor that eliminates the necessityof a capping mechanism for the rotor cavity.

SUMMARY OF THE INVENTION

The present invention relates to an adapter having an axis therethroughfor supporting a centrifuge tube within a cavity in a centrifuge rotor.The cavity itself has an axis therethrough. The axis of the adapter may,in use, align in parallel relationship with the axis of the cavity. Theadapter comprises a first and a second adapter segment, each segmenthaving an exterior surface and a mating surface thereon. Each segmenthas an indentation in the mating surface thereof. The segments may beconnected by at least one hinge that supports the segments for relativepivotal movement about a hinge axis from an open to a mated position.The hinge axis extends perpendicular to the axis of the adapter.

When in the mated position the mating surfaces of the segments are incontacting relationship and the indentations therein cooperate to definea recess having a predetermined shape. In one embodiment of the adapterof the present invention, used with a centrifuge tube having a body witha neck thereon in which a portion of the neck has a constricted regionwhen the tube is capped, the indentation in each segment is shaped suchthat when the segments are in the mated position the recess is sized toclosely correspond to the configuration of at least the neck of thetube. In this embodiment at least one of the segments has a feature onthe mating surface thereof that projects into the indentation therein.When the segments are in the mated position and the neck of the tube isreceived within the adapter the feature is received within theconstricted region of the neck of the tube. A collar may be provided toprevent the bottoming of the tube in the cavity.

In another embodiment of the adapter of the present invention theindentation in each segment is shaped such that when the segments are inthe mated position the recess so defined is sized to closely correspondto the size and configuration of the centrifuge tube over its entirelength.

In another aspect the present invention relates to an adapter forsupporting a closed centrifuge tube having a predetermined size andconfiguration within a cavity in a vertical angle centrifuge rotor. Therotor is rotatable to a predetermined maximum speed. The adapter has acentral axis extending therethrough that, in use, aligns in parallelrelationship both with the axis of the rotor cavity in which the adapteris disposed and with the axis of rotation of the vertical angle rotor.The adapter comprises a first and a second adapter segment, each ofwhich has an exterior surface and a mating surface thereon. Each segmenthas an indentation in the mating surface thereof. The indentations areshaped such that when the segments are joined along their matingsurfaces the indentations cooperate to define a recess able to totallysurround a centrifuge tube disposed therein. Each adapter segment isfabricated of a material that has sufficient strength to withstand thevertical forces created by the pressure of a liquid undercentrifugation. Thus, use of an adapter in accordance with this aspectof the present invention permits a tube to be centrifuged in a verticalangle centrifuge rotor without the necessity of a capping mechanismbeing placed in the rotor cavity.

In still another aspect the mating surface on each adapter segmentdefines a predetermined angle with respect to a plane that is normal toa plane containing the line of action along which the adapter segmentsare joined. Inclination of the mating surfaces of the adapter segmentsallows the same to displace relative to each other to totally fill therotor cavity in which they are disposed without any separation beingdefined between the segments. Inclined mating surfaces may be providedon any of the adapter segments disclosed in the present application.

In still another aspect the present invention relates to an adapter forsupporting a closed centrifuge tube in which at least one of the adaptersegments has an effective weight sufficient to balance forces created bythe pressure of a liquid carried in the tube under centrifugation thatact transversely to the central axis. In use, with the adapter insertedinto a cavity of a rotor, the one segment is disposed closer to the axisof rotation so that the mating surfaces of the adapter segments lie in aplane that is perpendicular to a radius of the rotor extending throughthe cavity. In such a disposition the weight of the one segment whileunder centrifugation is sufficient to maintain the mating surfaces ofthe adapter segments in contacting relationship with each other.Suitable keying may be provided to identify the one segment having thepredetermined effective weight.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription thereof, taken in connection with the accompanying drawings,which form a part of this application and in which:

FIG. 1 is a perspective view of an adapter according to a firstembodiment of the present invention for supporting the neck region of acentrifuge tube of the type in which a portion of the tube neck has aconstricted region thereon when capped, the adapter being shown in theopen position;

FIG. 2 is a fragmentary elevation view, in section, of the tube adapterof FIG. 1 in use and supporting the neck portion of a centrifuge tube ina fixed angle rotor cavity;

FIG. 3 a perspective view of an adapter according to a second embodimentof the present invention for supporting the full length of a centrifugetube within a rotor cavity, the adapter being shown in the openposition;

FIG. 4 is a fragmentary elevation view, in section, of the tube adapterof FIG. 3 in use and supporting a centrifuge tube over its entire axiallength in a fixed angle rotor cavity;

FIG. 5 is a perspective view similar to FIG. 3 of a modification of theembodiment of the tube adapter there shown for use with an open toptube;

FIG. 6 is a fragmentary elevation view, in section, of the centrifugetube adapter of FIG. 5 in use and supporting a centrifuge tube over itsentire axial length in a fixed angle rotor cavity;

FIG. 7A is a perspective view of an adapter in accordance with anotheraspect of the present invention used to support a closed tube within thecavity of a vertical angle rotor, the adapter segments being independentof each other, while FIG. 7B is a modification of the embodiment ofadapter shown in FIG. 7A in which the adapter segments are hinged;

FIG. 8 is a fragmentary elevational view of an adapter shown in eitherFIG. 7A or 7B in use and supporting a centrifuge tube over its entireaxial length in a vertical angle centrifuge rotor cavity, with a portionof the tube being broken away;

FIGS. 9A and 9B are sectional views taken along section lines 9A--9A,9B--9B in FIG. 8 showing the inclination of the mating surfaces of theadapter segments, the view of FIG. 9A illustrating the relationship ofthe adapter segments with respect to each other, with respect to thetube received in the adapter, and with respect to the rotor cavity inwhich the adapter is placed while rotor is at rest while the view ofFIG. 9B shows the relationship of the adapter segments with respect toeach other, with respect to the tube received in the adapter, and withrespect to the rotor cavity in which the adapter is placed when therotor is rotating;

FIG. 10 is a perspective view of an adapter in accordance with yetanother aspect of the present invention used to support a closed tubewithin the cavity of a vertical angle rotor;

FIG. 11A is a side sectional view of an adapter of FIG. 10 in use andsupporting a centrifuge tube over its entire axial length in a verticalangle centrifuge rotor cavity, while FIGS. 11B and 11C are,respectively, sectional views of the adapter as shown in FIG. 11A takenalong section lines 11B--11B and 11C--11C; and

FIG. 12A is a perspective view of a modification of the embodiment ofthe adapter shown in FIGS. 10 and 11 with the inboard adapter segmenthaving a keying configuration thereon, while FIG. 12B is a sidesectional view of the adapter of FIG. 12A with the adapter segmentsjoined together;

FIG. 13 is a perspective view of another modification of the embodimentof the adapter shown in FIGS. 10 and 11;

FIG. 14 is an enlarged view of a portion of the perspective view of FIG.13 illustrating a hinge arrangement useful with the modified adaptorshown therein;

FIG. 15 is an enlarged view of the inboard segment of the modifiedadaptor shown in FIG. 13 taken along view lines 15--15 therein;

FIG. 16 is a side sectional view of an adapter of FIG. 10 in use andsupporting a centrifuge tube over its entire axial length in a verticalangle centrifuge rotor cavity.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following detailed description, similar referencenumerals refer to similar elements in all Figures of the drawings.Superscripted numerals generally relate to corresponding functionalelements or features throughout all of the Figures of the drawings.

FIG. 1 is an exploded perspective view of an adapter, generallyindicated by the reference character 10, according to a first embodimentof the present invention. The adapter 10 in accordance with thisembodiment is useful for supporting a centrifuge tube T of the typehaving a body portion B with a closed end C, the body B tapering througha transition region R to a narrowed neck region N. The neck N serves asthe liquid port through which a liquid under test may be loaded into thetube T. When the tube T is capped at least one portion D of the neck Nbecomes radially inwardly constricted, thereby forming a constrictedregion in the neck of the tube. Preferably the capping assemblydisclosed in U.S. Pat. No. 4,552,278 (Romanauskas) is used to cap thetube, so that the neck N of the tube has a corrugated configurationimparted thereto. The corrugated configuration has at least one andoptionally a plurality of circumferentially extending corrugationsformed in the neck N. It should be understood that any other cappingarrangement may be used, so long as any form of constricted region isimparted to the configuration of the neck N.

The adapter 10 is comprised of a first adapter segment 12 and anidentical second adapter segment 14. Each segment 12, 14 has an exteriorsurface 16 and a planar mating surface 18 thereon. The exterior surface16 of each segment is defined by a generally cylindrical lateral surfaceportion 20 and a planar upper surface portion 22. In the preferredinstance an enlarged collar 24 is disposed intermediate the lateralsurface portion 20 and the upper surface portion 22. When the segments12, 14 are mated together the mating surfaces 18 thereof are joined inabutting contact. As will become clearer herein the member so producedhas an axis 10A (best seen in FIG. 2) extending therethrough. As is bestseen in FIG. 2 the configuration and size of the adjacent lateralsurface portions 20 closely corresponds to the configuration anddiameter of a rotor cavity 40 in which the adapter 10 is used. The uppersurface portions 22 of the conjoined segments are accessible when theadapter 10 is received in the rotor cavity 40.

The segments 12 and 14 are connected and supported for relative pivotalmovement with respect to each other by at least one hinge 26. The hinge26 may take the form of a live hinge bridging the upper surface portions22 of the segments 12, 14, or may, if desired, take the form of a coinedhinge. The term "live hinge" refers to a hinge type, typically made of apolypropylene material, which must be flexed or bent before the plasticis cooled or permanently set. Such hinges are complete without secondaryoperations. The term "coined hinge" refers to a hinge that iscold-formed, usually by a stamping operation. The stamping operationcreates a narrower and a thinner flexing region which defines a hinge.These forms of hinges are defined in the Handbook of Plastics andElastomers, McGraw-Hill Book Company 1975, (Charles A. Harper, Editor)at page 12-9.

However formed, in accordance with the present invention the axis 26A ofthe hinge 26, that is, the axis about which occurs the relative pivotalmotion of the segments, extends perpendicular to the axis 10A of theadapter 10. This relationship of the hinge axis 26A to the axis 10A ofthe adapter 10 is best illustrated in FIG. 2.

The mating surface 18 of each of the adapter segments 12, 14 has anindentation 28 therein. The indentation 28 in each segment 12, 14corresponds to the size and contour of at least a portion of the tube T.Thus, when the segments 12, 14 are mated, the indentations 28 thereincooperate to define a recess 30 (FIG. 2) that corresponds to the sizeand shape of at least a predetermined portion of the tube T that isreceived therein.

In the embodiment of FIG. 1, in which the adapter 10 is configured andsized to support only the neck N and the transition region R of the tubeT, at least one but preferably both indentations 28 contains a feature34, in the form of a circumferentially extending ridge, that correspondsin size and is located complementarily to the position of theconstriction D in the neck N of the tube.

The adapter 10 shown in FIGS. 1 and 2 is especially useful when thediameter body B of the tube T is equal to the diameter of a cavity 40 ina centrifuge rotor 42, but the overall length L of the tube T is lessthan the axial length of the cavity. The rotor cavity 40 has an axis 40Atherethrough that aligns in parallel relationship with the axis 10A ofthe adapter 10 when the same is disposed therein. In use, as is bestseen in connection with FIG. 2, the adapter 10 defined by the matedsegments 12, 14 serves to support the neck N and the transition region Rof the tube T within the cavity 40.

To mount the tube T in the cavity, the tube T is inserted into one ofthe segments 12, 14, so that the feature 34 on the segment(s) isreceived within the constricted region D in the neck N of the tube Twhen the segments are in the mated position. The segments 12, 14 arethen pivoted about the hinge axis 26A to place the mating surfaces 18thereon in abutting contact. This closes the adapter 10 around the tubeT and thus permits the tube T to be manipulated by manipulation of theadapter 10. The tube T and the adapter 10 are then axially inserted intothe cavity 40. In the preferred instance the tube T bottoms against theclosed end of the cavity 40.

The axial length of the adapter 10 is selected such that when the tube Tis received in the cavity 40, the upper surface portions 22 on thesegments 12, 14 are accessible to a user. The hinge 26 may be formed soas to define a useful lifting appliance, as shown in FIG. 2. Thus, towithdraw the tube T at the end of a centrifugation run, a user graspsthe hinge 26 and lifts the tube from the cavity 40. It should beappreciated from the foregoing that the feature 34 in such an instancedefines a lifting surface which acts against the material of the tube inthe constricted region D in the neck N thereof, and thus serves totransmit the lifting force to the tube T to withdraw the same from thecavity. The tube T may be withdrawn without unduly agitating theseparation within the tube T.

In some cases the rotor 42 may have a shoulder 44 defined about themouth of the cavity 40. The shoulder 44 is preferably located on therotor 42 at a position that is axially beneath the collars 24 on thesegments 12, 14 when the adapter is received within the cavity, therebyto guard against the possibility that tube rupture will permit theadapter 10 to enter into the cavity 40.

The segments 12, 14 with the hinge 26 therebetween are preferablyintegrally formed from a suitable material, such as polypropylene. Ofcourse, the segments 12, 14 may be otherwise fabricated from one or morepieces, using other manufacturing techniques and other materials, andassembled to define the adapter 10. Similar techniques may be used toform any other embodiment of the adapter illustrated and discussedherein.

For those instances wherein the diameter of the tube T is less than thecorresponding diameter of the cavity 40 the adapter 10' shown in FIGS. 3and 4 finds utility. In this embodiment of the invention the recess 30'(FIG. 4) formed by the cooperative association of the indentations 28'in the mated adapter segments 12', 14' is configured to correspond tothe size and shape of the tube T over the entire axial length L'thereof. For this purpose the segments 12', 14' are each provided withan axial extension 36 having a bottom wall 38. The bottom wall 38 neednot completely close the bottom of the adapter 12', 14', as illustrated,but may only partly close the same. The presence of the extension 36 andthe bottom wall 38 permit the recess 30' defined when the segments 12',14' are joined to receive the entire axial length L' of the tube T'.

FIG. 4 illustrates this embodiment of the invention in use. When thetube T is received in the recess 30' the closed end C' of the tube T' iscontacted by the interior surface of the bottom wall 38. Preferably theindentations 28' in the segments 12', 14' are placed such that the tubeT' lies as close to the bottom of the rotor cavity 40, thereby tomaximize the centrifugal force imposed on the liquid sample. It shouldalso be noted that in this embodiment of the invention the feature 34present in the embodiment of FIG. 1 is not required, since the requisitelifting force transmission surface is defined by the bottom wall 38operating against the bottom end C' of the tube T'. It is also notedthat in this embodiment of the invention the collar 24 may beeliminated.

FIG. 5 illustrates an adapter 10" that defines a modification of theembodiment of the invention shown in FIG. 3. In this embodiment, thetube T" has the form of a test tube, with no constriction present todefine a neck. In this instance, the segments 12", 14" are modified toexhibit indentations 28" similar to those shown in FIG. 3, but whichcorrespond in size and shape to the test tube T" over the entire axiallength L" thereof.

In whatever one of the embodiments used, the hinge between the segmentsis disposed on the upper surface portion of the exterior surface of theadapter segments. Such a disposition is believed advantageous in that itlocates the hinge at a position where the hinge does not interfere withthe receipt of the adapter within the rotor cavity. At the same time thehinge defines a useful lifting appliance.

Although the adapter previously illustrated and discussed may findutility in the environment of a vertical angle rotor, such a utilizationmay typically require the provision of a suitable capping arrangement toprevent tube failure. The capping arrangement is required in the casethat the adapter does not completely surround the tube, such as shown inFIGS. 1 and 2. However, a capping arrangement is also required if theadapter does completely surround the tube, as shown in FIGS. 3 through6, but does not have sufficient strength to withstand the vertical forcedue to liquid pressure under centrifugation.

As outlined earlier, a capping arrangement may be viewed asdisadvantageous for various reasons. Accordingly, it is believeddesirable to provide an adapter able to support a closed tube T in avertical angle rotor without the necessity of a capping arrangement.FIGS. 7A and 7B illustrate such an adapter in accordance with anotheraspect of the present invention. FIG. 7A illustrates an unhingedembodiment of the vertical angle rotor adapter, while FIG. 7B shows ahinged embodiment thereof.

The vertical angle rotor adapter shown in FIGS. 7A and 7B is generallyindicated by the reference character 10³ and is generally similar to theadapters 10' and 10" discussed in connection with FIGS. 3 and 5 in thesense that the adapter 10³ is arranged to totally surround the tube Tdisposed therewithin. The adapter 10³ comprises a first adapter segment12³ and a second adapter segment 14³. Each segment 12³, 14³ has anexterior surface 16³ thereon. The exterior surface 16³ of each segment12³, 14³ is defined by a generally cylindrical lateral surface portion20³ and a planar upper surface portion 22³.

In accordance with the embodiment of the invention shown in FIGS. 7A and7B the adapter segment 12³ has a planar mating surface 18³ thereon whilethe adapter segment 14³ has a planar mating surface 19³ thereon. For areason which is explained more fully herein the mating surfaces 18³ and19³ on the segments 12³ and 14³, respectively, are angled with respectto a predetermined reference plane, to be defined. The inclination ofthe mating surfaces 18³ and 19³ on the segments 12³ and 14³,respectively, is believed best seen in FIGS. 9A and 9B. It should beunderstood that the mating surfaces of the adapter segments in any ofthe embodiments shown in FIGS. 1 through 6 may also be inclined in themanner shown in FIGS. 9A and 9B.

The mating surfaces 18³ and 19³ of each of the adapter segments 12³ and14³, respectively, each have an indentation 28³ therein. The indentation28³ in each segment 12³ and 14³ corresponds to the size and shape of theentire axial length L of the tube T. Thus, when the segments 12³ and 14³are mated the indentations 28³ therein cooperate to define a recess 30³(FIG. 8) that corresponds to the size and shape of the entire axiallength of the tube T (FIGS. 1 and 8) that is received therein. That isto say, the indentations 28³ in each segment are shaped such that whenthe segments 12³ and 14³ are joined along their respective matingsurfaces 18³ and 19³ the indentations 28³ in each segment cooperate todefine a recess 30³ able to totally surround a centrifuge tube Tdisposed therein.

FIG. 8 illustrates the adapter 10³ in accordance with this aspect of thepresent invention in use in the environment of a vertical anglecentrifuge rotor 42^(V). In such a rotor the axis of each cavity 40^(V)is parallel or approaching parallel (with an inclination angle of notmore than fifteen (15) degrees) to the axis of rotation A of the rotor.As seen from FIG. 8 the adapter 10³ has a central axis 10³ A that, inuse, aligns with the axis of the cavity 40^(V) in which it is disposedand with the axis of rotation A of the vertical angle rotor 42^(V).

In the embodiment of the invention shown in FIG. 7A the segments 12³,14³ are independent of each other. These segments 12³, 14³ may be joinedby moving each segment toward the other along a line of action 48thereby to bring the mating surfaces 12³, 14³ thereof in abuttingcontact. As used herein the term "line of action" is meant to denotethat direction of motion which joins the segments 12³, 14³ such that, ina given predetermined plane perpendicular to the central axis 10³ Asimultaneous contact of both sides of the segments 12³, 14³ occurs.

In FIG. 7B the segments 12³, 14³ are connected and supported forrelative pivotal movement with respect to each other by at least onehinge 26³. The pivotal axis 26³ A (FIG. 8) of the hinge 26³, that is,the axis about which occurs the relative pivotal motion of the segments12³, 14³, extends perpendicular to the axis 10³ A of the adapter 10³. Asdiscussed earlier the hinge 26³ may take the form of a live hingebridging the upper surface portions 22³ of the segments 12³, 14³, ormay, if desired, take the form of a coined hinge. Accordingly thesegments 12³, 14³, as shown in the embodiment of FIG. 7B may also bejoined by moving each segment toward the other along the line of action48. In the embodiment of FIG. 7B it is noted that the line of action 48also lies in the plane perpendicular to the pivotal axis 26³ A of thehinge 26³.

With reference to the sectional views of FIGS. 9A and 9B, theinclination of the surfaces 18³, 19³ may be most clearly seen.(Sectioning of the adapter has been omitted from FIGS. 9A and 9B forclarity of illustration). When the segments 12³, 14³ are joined, thetube T is totally surrounded by the adapter 10³. By inclining the matingsurfaces 18³, 19³ the segments 12³, 14³ may expand during centrifugationto fill the entirety of the rotor cavity 40^(V). Thus, any variations inthe size of the various cavities 40^(V) in a given rotor, variations incavity size from rotor to rotor, and variations in the thickness of thesegments from adapter to adapter may be accommodated without breakingthe total containment of the tube T by the adapter.

It is also clear from FIG. 9A that when the segments 12³, 14³ are matedthe interior surface of the interior recess 30³ of the adapter 10³ isinterrupted by the inwardly projecting corners 50 on the mating surface19³ of the segment 14³. The corners 50 lie inwardly of the correspondingcorners 52 defined on the mating surface 12³. The radial distance R₁measured between the central axis 10³ A and the interior surface of theadapter segment 14³ in the region of the indentation 28³ therein is lessthan the radial distance R₂ measured between the central axis 10³ A andthe interior surface of the adapter segment 12³ in the region of theindentation 28³ therein. For reference purposes it is convenient at thispoint to define the radial distance R₃ as the distance between thecentral axis 10³ and the exterior surface of the adapter segment 14³ inthe region of the indentation 28³ therein and the radial distance R₂ asthe distance between the central axis 10³ and the exterior surface ofthe adapter segment 12³ in the region of the indentations 28³ therein.The thickness of the segment 12³ is equal to the difference between thedistances R₄ and R₂, while thickness of the segment 14³ is equal to thedifference between the distance R₃ and R₁.

To accommodate the instance where the rotor cavity 40^(V) is at itslargest possible tolerance and the thickness of the segments of theadapter are at their smallest possible tolerance, the arc length of theinner surface of the segment 14³ (i.e., the distance between the points50--50) in a plane perpendicular to the adapter axis 10³ A (the plane ofFIG. 9A) plus the arc length of the inner surface of the segment 12³(i.e., the distance between the points 52--52) in the same plane mustequal the circumference of the inside of the adapter in a planeperpendicular to the adapter axis 10³ A in the case when the adapter ofthe smallest segment thickness is conformed to the largest rotor cavity,as illustrated in FIG. 9B.

The magnitude of angles of inclination of the surfaces may be measuredby reference to a reference plane 54. The reference plane 54 is thatplane that contains both the vertical central axis 10³ of the adapter10³ and at least one of the inwardly projecting corners 50 of theadapter segment 14³. Alternatively, the reference plane 54 may bedefined as the plane that is normal to the line of action 48(superimposed on FIG. 9A) along which the segments 12³, 14³ are joinedtogether. Measured with respect to the reference plane 54 theinclination of the surfaces 18³ and 19³ lies in the range of angles fromabout 10 to about 80 degrees. Preferably, each angle is forty five (45)degrees.

It should be noted that although the surfaces 18³ and 19³ are shown asbeing inclined to the same degree (i.e., the angles of the surfaces 18³and 19³ with respect to the reference plane 54 are equal), such is notnecessarily required. It is only necessary that the inclination of thesurfaces 18³ and 19³ be such that the segments are maintained in mutualcontact if they expand during centrifugation to fill the cavity 40^(V).It should also be noted that the segments 12³ and 14³ may be other thancircular, and can be ellipsoidal, if desired.

An adapter in accordance with this embodiment of the present inventionmay be fabricated from any suitable material so long as the resultingadapter has sufficient strength (as that term is defined herein). Thematerial of choice must exhibit other desirable properties, such asappropriate ultimate strength, appropriate modulus of elasticity,suitable chemical compatibility with any liquid sample being centrifugedand ability to withstand autoclaving. Suitable plastic materials includepolypropylene, polyamide, acetal, polyphenylene oxide, polyvinylchloride, polycarbonate or polyethylene. Other plastic or metallicmaterials (either homogeneous (neat) or fiber reinforced) with similaror better mechanical and chemical properties for the application underconsideration may also be used. The adapter may be formed in anyconvenient manner consistent with the material selected, such asmolding, machining, casting or forging.

In order to support a tube T in a vertical angle rotor without theassistance of the restraining force provided by a capping mechanism, theadapter 10³ must exhibit sufficient strength to absorb the forcesimposed on the tube T by the pressure of the liquid therein. Thus, asthe term is used herein, "sufficient strength" means that the adaptermust be able to withstand the forces imposed on it during centrifugationwithout failing or deforming to the extent that the tube carried thereinruptures.

Whether a given adapter is of sufficient strength, and thus falls withinthe scope of the claims of the present invention, can be determined fromvarious readily ascertainable operating parameters of the vertical anglerotor in which the adapter is to be used and the application to whichthe adapter is to be put. These parameters are the specific weight ofthe liquid sample within the tube received by adapter, the radius R_(i)which represents the minimum distance to the sample from the axis A ofrotation (FIG. 8), the diameter D_(o) (FIG. 8) of the rotor cavity, thethickness of the adapter segment, the inside diameter of the tube, andthe speed of rotation of the vertical angle rotor.

The pressure at any location across the diameter of the tube in whichthe liquid sample is disposed is ##EQU1## where

P is the pressure (psi),

ω is the rotational velocity of the rotor (radians per second),

g is acceleration due to gravity (inches per second²),

α is the specific weight of the sample (Lb per inch³),

R_(o) is the distance to the point of interest x where the pressurevalue is desired from the center of rotation (inches), and

R_(i) is the minimum distance to the sample from the axis A of rotation(inches).

The total vertical force F_(V) that the adapter must withstand is thenfound by integrating this pressure function over the circular crosssectional area of the inside of the tube.

Knowing the adapter dimensions and the force F_(V), the average stressin the wall of the adapter can be determined in accordance with therelationship: ##EQU2## where

s is the stress (psi),

F_(V) is the force (Lbf)

D_(o) is the diameter of the rotor cavity, and

D_(i) is the inside diameter of the adapter when operating at speed,which equals the diameter of the rotor cavity minus the thickness ofeach of the segments of the adapter (FIG. 9B).

Based on the identity of the material used in the given adapter, themodulus of elasticity of that material may be readily obtained. Anestimation of the vertical deformation of the adapter may be found bymultiplying the initial length of the adapter by the average stressdivided by the modulus of elasticity of the adapter material. If theaverage stress calculated in Equation (2) is less than the ultimatestrength of the adapter material, and the predicted deformation is lessthan the deformation that will cause first leakage in the tube carriedwithin the adapter, then the given adapter is to be construed to havesufficient strength for at least one operating cycle, and thereforefalls within the contemplation of the present invention. Thedetermination of sufficient strength as set forth above under operatingconditions will verify both the analysis and the conclusion of thesufficiency of strength of the adapter.

It should be understood that it is within the contemplation of thisinvention to use an adapter in accordance herewith to support a tube ora predetermined portion thereof within a swinging bucket, thereby makingthe use of the adapter in accordance with this invention amenable foruse in the environment of a swinging bucket rotor.

To recapitulate, the adapter heretofore described in connection withFIGS. 7A through 9B for use primarily in a vertical angle rotor isfabricated of a material and in a manner such that the adapter, whileunder centrifugation, has sufficient strength to withstand the verticalforce F_(V) (that is, forces that act parallel to the central axis ofthe adapter). Vertical stresses in the tube T are therefore minimized.Angled mating edges on the adapter segments (FIGS. 7A and 9A) areprovided to prevent a separation from forming between the segments inresponse to the radial expansion of the tube under pressure. Theprevention of such a separation insures that the tube is supported aboutthe entirety of its circumference such that the possibility of tubefailure is minimized.

As yet another alternative embodiment of the present invention, theadapter may be designed and fabricated such that, under centrifugation,the body force of one adapter segment is sufficient to balance the forcecreated by the pressure of a liquid carried in the tube underconfiguration that acts transversely to the central axis. As will bedeveloped, when in use the preferred form of such an adapter must bedisposed within a cavity of a rotor in an orientation such that themating surfaces of the adapter segments lie in a plane that issubstantially perpendicular to a radius of the rotor extending throughthe cavity. In such an orientation the line of action of closure of thepreferred form of such an adapter aligns with a radial line extendingfrom the axis rotation of the rotor to the center of the cavity in whichthe adapter is disposed.

FIG. 10 illustrates a preferred arrangement of a split adapter 10⁴ foruse in a vertical angle rotor in accordance with this embodiment of thepresent invention. The structure of the adapter 10⁴ is generally similarto the adapter 10' shown and discussed in connection with FIGS. 3A and3B and to the adapter 10³ shown and discussed in connection with FIGS.7A and 7B in the sense that the adapter 10⁴, like the adapters 10' and10³, is arranged to totally surround a tube T disposed therewithin.

Structurally, the adapter 10⁴ includes a first adapter segment 12⁴ and asecond adapter segment 14⁴. Each segment 12⁴, 14⁴ has an exteriorsurface 16⁴ and a mating surface 18⁴ thereon. The exterior surface 16⁴of each segment 12⁴, 14⁴ is defined by a generally cylindrical lateralsurface portion 20⁴ and a planar surface portion 22⁴. The exteriorsurface 16⁴ of each segment 12⁴, 14⁴ is sized and shaped for closefitting receipt within the cavity 40^(V) of a vertical angle rotor42^(V) (FIGS. 11A through 11C).

Each segment 12⁴, 14⁴ is provided with an indentation 28⁴ in the matingsurface 18⁴ thereof. The indentation 28⁴ in each segment 12⁴, 14⁴ isshaped so that when the segments 12⁴ and 14⁴ are joined along theirmating surfaces 18⁴ the indentations 28⁴ cooperate to define a recess30⁴ able to totally surround a centrifuge tube T disposed therein. Theadapter 10⁴ has a central axis 10⁴ A extending therethrough (FIG. 11A).As will be discussed later, the recess 30⁴ may be inclined with respectto the central axis 10⁴ A and remain within the contemplation of thisinvention.

The mating surfaces 18⁴ of the segments 12⁴, 14⁴ need not be angled withrespect to the reference plane as discussed previously in connectionwith FIGS. 9A, 9B, although they may be so arranged if desired.Alternatively or additionally, it should be noted that an adapter 10⁴ inaccordance with this embodiment of the present invention may be providedwith a hinge on the upper surface 22⁴ of the segments, similar to theembodiment shown in FIG. 7B. If a hinge is provided, the pivotal axis ofthe hinge extends perpendicular to the axis of the adapter. As discussedearlier, the hinge may take the form of a live hinge or a coined hinge.

In accordance with this embodiment of the invention, at least one of thesegments of the adapter 10⁴ must have a predetermined effective weightunder centrifugation that is sufficient to prevent separation of theadapter segments. The effective weight of the adapter segment is definedas the weight of the segment at sea level multiplied by the g (gravity)force imposed on the segment when the same is rotated at a predeterminedoperating speed with the center of mass of the segment lying apredetermined radial distance from an axis of rotation.

At least one, but preferably, both of the segments 12⁴, 14⁴ has at leastone, but preferably, a pair of resilient extensions 58⁴, 60⁴,respectively, thereon. In the preferred case the resilient extensions58⁴, 60⁴ are flexibly mounted, as by hinging, to the outside surface 16⁴of the segment along a line of bending 62⁴. The resilient extensions58⁴, 60⁴ are biased to flare outwardly from the adapter segment, and arebendable along the line of bending 62⁴ to close inwardly toward thelateral surface portion 20⁴ of the outside surface 16⁴ of the segment towhich they are attached. In the closed position the resilient extensions58⁴, 60⁴ are in contact with the lateral surface portion 20⁴ of theoutside surface 16⁴ of the segment to which they are attached. The lowerend of each extension is tapered, as at 64⁴. It should be noted thatwhen the adapter segments 12⁴, 14⁴ are mated the edges of resilientextensions 58⁴, 60⁴ are circumferentially spaced a slight distanceapart, thereby to provide sufficient clearance to accommodate theflexing motion of the resilient extensions 58⁴, 60⁴ during insertioninto the rotor cavity. As will become clearer herein each extension 58⁴,60⁴ serves to frictionally interact with the boundaries of a rotorcavity 42^(V) (FIGS. 11A through 11C) to prevent rotation of the adapter10⁴ about its axis 10⁴ A with respect to the body of the rotor 40^(V)thereby to maintain the adapter 10⁴ in a predetermined angularorientation within the cavity during operation of the rotor.

FIGS. 11A through 11C illustrate the adapter 10⁴ of FIG. 10 in use in acavity 40^(V) of a vertical angle centrifuge rotor 42^(V). Sectioning ofthe adapter has been omitted from FIG. 11C for clarity of illustration.When disposed in the rotor 42^(V) the segment (for example, the segment12⁴) which lies closer to the axis of rotation A of the rotor is termedthe "inboard" segment. The other segment 14⁴ which lies farther from theaxis of rotation 10A is termed the "outboard" segment. The inboardsegment 12⁴ must have an effective weight sufficient to balance theforce F_(T) created by the pressure of a liquid carried in the tubeunder centrifugation that acts transversely to the central axis 10⁴ A ofthe adapter 10⁴. Such an arrangement precludes separation of the adaptersegments 12⁴, 14⁴ during centrifugation. When properly positioned in thecavity 40^(V) of the rotor 42^(V) the mating surfaces 18⁴ of the adaptersegments 12⁴, 14⁴ are disposed so as to lie in a plane 68 (FIG. 11A)that is substantially perpendicular to a radius of the rotor 42^(V)extending through the cavity 40^(V). The plane 68 is the plane of FIG.11B.

It should be noted that in some instances the recess 30⁴ may be arrangedwithin the adapter 10⁴ such that an axis extending centrally through therecess 30⁴ of the adapter 10⁴ is offset radially with respect to theaxis 10⁴ A of the adapter 10⁴. In such an arrangement the recess 30⁴ isnot concentric with the generally cylindrical lateral surface portion20⁴ of the adapter 10⁴. If so offset it its preferred that the recess30⁴ be displaced radially outwardly with respect to the axis 10⁴ A ofthe adapter 10⁴. Such an arrangement may be utilized to increase theeffective weight of the inboard segment 12⁴ and/or to dispose the sampleto higher g-forces resulting from the increased radial distance to thesample.

Whether the inboard adapter segment 12⁴ has an effective weightsufficient for the purpose of containing the transverse force F_(T), andthus fall within the scope of the claims of the present invention, canbe determined from consideration of the identical operating parametersas previously developed and described in connection with the "sufficientstrength" determination for accommodation of the vertical force F_(V).

As earlier noted the pressure P across the diameter of the tube isdefined by Equation (1). The value of the pressure P ranges from zero atthe inboard edge of the tube to a maximum value at the farthest radiallocation of the liquid sample from the axis of rotation of the rotor.The inboard segment 12⁴ of the adapter 10⁴ is subjected to a radiallyinwardly directed force F_(T) that results from liquid pressure in theboard half of the tube. The magnitude of this radially inwardly directedforce F_(T) is determined by integrating the component of the pressurefunction defined by Equation (1) that is parallel to a radial linethrough the center of mass of the inboard segment 12⁴ over the surfacearea of the indentation 28⁴ of the adapter segment 12⁴. So long as theeffective weight of the inboard segment 12⁴ is equal to or greater thanthe force F_(T) due to liquid pressure, then centrifugal force effectsacting on the inboard segment 12⁴ cause the mating surfaces 18.sup. 4 ofthe adapter segments 12⁴, 14⁴ to remain in contacting relationship. Theadapter 10⁴ will thus maintain complete containment of the tube duringoperation of the rotor.

An adapter 10⁴ having segments 12⁴, 14⁴ in accordance with thisembodiment of the invention may be fabricated from any suitable materialso long as the resulting adapter segment 12⁴ has sufficient effectiveweight (as that term is defined herein) and exhibits suitable chemicalcompatibility with any liquid sample being centrifuged. It shouldpreferably have the ability to withstand sterilization, as byautoclaving. Suitable plastic materials include polypropylene,polyamide, acetal, polyphenylene oxide, polyvinyl chloride,polycarbonate or polyethylene. Other plastic or metallic materials(either homogeneous (neat) or fiber reinforced) with similar or bettermechanical and chemical properties for the application underconsideration may also be used. The adapter may be formed in anyconvenient manner consistent with the material selected, such asmolding, machining, casting or forging.

It should be noted that both the segments 12⁴, 14⁴ may be substantiallyidentical in weight or they may be substantially different in weight, solong as the inboard adapter segment has the requisite effective weightto completely contain the tube T during operation of the rotor.

Although not required of this embodiment, it is preferred that theadapter 10⁴ also be fabricated of a material that has sufficientstrength to withstand the vertical force F_(V) due to liquid pressureunder centrifugation, as discussed in connection with FIGS. 7A through9B. Of course, if the adapter 10⁴ is not able to withstand the verticalforce F_(V), then a separate capping arrangement on the rotor isrequired.

By providing the inboard segment 10⁴ having a suitable effective weightthe mating surfaces on the inboard and outboard segments remain incontact during operation of the rotor and no gap therebetween may form.The tube T is thus completely contained within the conjoined adaptersegments during operation of the rotor, and the possibility of tubefailure due to extrusion into a gap is precluded. The present embodimentcarries the additional benefit of minimizing circumferential stress inthe tube caused by the pressure of the liquid, therefore furtherreducing the possibility of tube failure. Since the effective weight ofthe inboard segment of the adapter is at least as great as thetransverse force due to pressure F_(T), the inboard segment limitsexpansion of tube. Greater tube reliability over a greater range oftube, adapter and cavity tolerances is thus produced.

As previously mentioned, the adapter 10⁴ must be disposed in the cavity40^(V) of the rotor 42^(V) in an orientation which substantially alignsthe line of action 48 of closure of the adapter segments 12⁴, 14⁴ with aradial line extending from the axis of rotation of the rotor to thecenter of the cavity 40^(V) in which the adapter is disposed and whichplaces the mating surfaces 18⁴ of the adapter segments 12⁴, 14⁴ in theplane 68 (FIG. 11A) that is perpendicular to the radius extendingthrough the cavity 40^(V). To meet this need, the segments 12⁴, 14⁴ maybe keyed in a fashion to be described.

If both segments 12⁴, 14⁴ have the requisite effective weight sufficientto ensure complete containment of the tube in the adapter recess, theneither segment may assume the position of the inboard segment. Thus, theadapter may be inserted into the cavity in either of two differentorientations and the desired performance will occur.

The keying can be implemented by providing any suitable distinctivephysical feature on the adapter, such as a visually distinctive markingor a distinctive shape.

Should only one segment 12⁴ exhibit the requisite effective weight thena form of keying is necessary which both: (1) identifies that segment asthe inboard segment; and (2) aligns the mating surfaces 18⁴ of theadapter segments 12⁴, 14⁴ in the plane 68.

A particular modified configuration of an adapter 10⁴ in which only onesegment 12⁴ exhibits the requisite effective weight is illustrated inFIGS. 12A and 12B. In this modification the inboard adapter segment 12⁴has a distinctive configuration imparted thereto in the form of the flatsurfaces 68⁴ provided on the exterior surface 16⁴ of the segment 12⁴.The cavity 40^(V) into which the adapter 10⁴ of FIG. 12 is insertable iscorrespondingly shaped, thus to ensures that the adapter 10⁴ is properlyreceived into the rotor 42^(V).

In addition, a portion of the upper surface 22⁴ of the inboard segment12⁴ is removed to define a channel 70⁴ therein. The mating surfaces 18⁴on the inboard segment 12⁴ are flush with the boundaries of the channel70⁴. The upper surface 22⁴ of the outboard segment 14⁴ is provided witha projecting flange 72⁴ that is shaped in correspondence to the channel70⁴. In addition, the mating surfaces 18⁴ on the outboard segment 14⁴are arranged to slidably engage the corresponding mating surfaces 18⁴ onthe inboard segment 12⁴. The undersurface of the flange 72⁴ has a pocket76⁴ therein that accepts the upper capped end of the tube T.

This structure defines a compact, cartridge-like adapter 10⁴ for thetube T. When the segments are separated, the tube T is retained in theoutboard segment 14⁴ with the capped end of the tube T received in thepocket 76⁴ therein. This disposition is believed to facilitate handlingof the tube T.

As briefly noted earlier, it may be desirable in some instances toorient the indentations within each adapter segment such that a centralaxis through the recess formed when the segments are joined is inclinedto the axis of the adapter. Such an adapter may be useful in convertinga vertical angle rotor to a rotor having a "near vertical" cavityorientation. The mating surfaces of the segments in such a case willline in a plane that contains the axis of the recess, said plane alsobeing inclined with respect to the axis of the adapter. These matingsurfaces of such an adapter need not, therefore, align with the planeperpendicular to a radius extending from the axis of rotation of therotor through the center of the cavity, as is the case in connectionwith the preferred embodiment of this aspect of the invention as shownin FIGS. 10 through 12. It should be understood, however, that so longas the effective weight of the inboard segment while undercentrifugation is sufficient to maintain the mating surfaces of theadapter segments in contacting relationship with each other, such amodified "near vertical" adapter lies within the contemplation of thepresent invention as defined by the appended claims.

FIGS. 13, 14, 15 and 16 illustrate another modified configuration for acompact, cartridge-like adapter 10⁴ similar to that shown in FIGS. 12Athrough 12B. The adapter 10⁴ includes adapter segments 12⁴, 14⁴, each ofwhich has an exterior surface 16⁴ and a mating surface 18⁴ thereon. Whenthe segments 12⁴, 14⁴ of the adaptor 10⁴ are conjoined the exteriorsurface 16⁴ has a cylindrical configuration similar to the adaptor ofFIG. 11C (without the resilient extensions 58⁴ and 60⁴) and is thusinsertable in a correspondingly shaped cylindrical rotor cavity 40^(V)(FIG. 16).

Similar to the case shown in FIGS. 12A and 12B, the mating surfaces 18⁴include those planar surfaces of the adapter segments 12⁴, 14⁴ thatalign in the plane 68 (perpendicular to the radius of the rotor 42⁴)when the adapter is received within the rotor, as well as planar lateralsurfaces that extends generally perpendicular thereto. The former areindicated in the Figures by the character 18⁴ and 18^(4') respectively.The mating surface 18⁴ in each segment is provided with an indentation28⁴ that cooperate to define a recess 30⁴ sized to accept a centrifugetube T therein. As is also the case with the arrangement of FIGS. 12A,12B, in the adapter 10⁴ of FIGS. 13 through 16 only one segment, e.g.,the inboard segment 12⁴, exhibits the requisite effective weight toinsure that the mating surfaces 18⁴ on the inboard segment 12⁴ and theoutboard segment 14⁴ remain in contact during operation of the rotor sothat no gap therebetween may form.

In the arrangement of FIGS. 13 through 16 a portion of the upper surface22⁴ of the outboard segment 14⁴ is removed to define the channel 70⁴therein. The upper surface 22⁴ of the inboard segment 12⁴ is providedwith the projecting flange 72⁴ that is shaped in correspondence to thechannel 70⁴. The lateral portions 18^(4') of the mating surfaces 18⁴ onthe inboard segment 12⁴ are arranged to slidably engage thecorresponding lateral portions 18^(4') of the mating surfaces 18^(4') onthe outboard segment 14⁴. The undersurface of the flange 72⁴ may have apocket 76⁴ therein that accepts the upper capped end of the tube T.Thus, when the segments 12⁴, 14⁴ are separated a tube T is retained inthe inboard segment 12⁴

The projecting flange 72⁴ on the upper surface 22⁴ of the inboardsegment 12⁴ has gripping serrations 80⁴ provided thereon. These grippingserrations 80⁴ facilitate manipulations of the segments. In addition thepresence of the serrations 80⁴ serves as a visual indicator key whichboth identifies the inboard segment and aligns the mating surfaces 18⁴of the adapter segments 12⁴, 14⁴ in the plane 68. As perhaps best seenin FIG. 15 a portion 82⁴ of the flange 72⁴ also projects forwardlythereby to overhang exterior surface 16⁴ on the inboard segment 12⁴. Asis seen in FIG. 16 when the adaptor 10⁴ is received within the cavity40^(V) of the vertical rotor 42^(V) the forwardly projecting portion 82⁴abuts against a shelf 45^(V) that is formed about the mouth of thecavity on the inboard side thereof. It should abe understood by thoseskilled in the art that an adapter as shown in FIGS. 10 through 16 canalso be used in rotors other than vertical rotors.

As briefly noted earlier, the segments 12⁴, 14⁴ may be hinged. Since theserrated flange 72⁴ is located at the upper end of the cartridge adaptor10⁴ a more convenient form of hinge arrangement 26⁴ is shown in FIGS. 13and 14. The hinge arrangement 26⁴ includes a pair of stub-like axles 86⁴disposed opposed lateral surface portions 18^(4') of the mating surface18⁴ of the inboard segment 12⁴. The hinge arrangement 26⁴ furtherincludes a pair of trunnion recesses 88⁴ provided on the opposedconfronting lateral surface portions 18^(4') of the mating surface 18⁴of the outboard segment 14⁴. The stub-like axles 86⁴ on the inboardsegment 12⁴ snappingly engage into the trunnion recesses 88⁴ on theoutboard segment 14⁴. The axis 26A⁴ of the hinge 26⁴ is perpendicular tothe axis of the adapter 10⁴ and supports the relative pivotal movement,about the hinge axis 26A⁴ of the segment 12⁴, 14⁴ with respect to theother from an open to a mated position.

The adapter 10⁴ of FIGS. 13-16 may be fabricated of the same material asused for the adapter 10⁴ of FIGS. 12A, 12B.

In connection with the arrangement of FIGS. 12A, 12B as well as FIGS.13-16 it should be understood that in some instances it may be desirableto orient the indentations within each adapter segment such that acentral axis through the recess formed when the segments are joined isinclined to the axis of the adapter. Such an adapter may be useful inconverting a vertical angle rotor to a rotor having a "near vertical"cavity orientation. The mating surfaces of the segments in such a casewill lie in a plane that contains the axis of the recess, said planealso being inclined with respect to the axis of the adapter. Thesemating surfaces of such an adapter need not, therefore, align with theplane perpendicular to a radius extending from the axis of rotation ofthe rotor through the center of the cavity, as is the case in connectionwith the preferred embodiment of this aspect of the invention as shownin FIGS. 10 through 12. It should be understood, however, that so longas the effective weight of the inboard segment while undercentrifugation is sufficient to maintain the mating surfaces of theadapter segments in contacting relationship with each other, such amodified "near vertical" adapter lies within the contemplation of thepresent invention as defined by the appended claims.

Those skilled in the art, having the benefit of the teachings of thepresent invention may impart numerous modifications thereto. It shouldbe understood that such modifications are also to be construed to liewithin the scope of the present invention, as defined by the appendedclaims.

What is claimed is:
 1. An adapter for supporting a closed centrifugetube within a cavity of a centrifuge rotor, the adapter comprising:afirst, inboard, adapter segment and a second, outboard, adapter segment,each segment having an exterior surface and a mating surface thereon,each segment having an indentation in the mating surface thereof, theindentation in each segment being shaped such that when the segments arejoined along their mating surfaces the indentations cooperate to definea recess able to totally surround a centrifuge tube disposed therein,the adapter having a central axis extending therethrough, and at leastone hinge connecting the segments and supporting the relative pivotalmovement, about a hinge axis, of at least one segment with respect tothe other from an open to a mated position, the hinge axis extendingperpendicular to the axis of the adapter, the hinge comprising a pair ofaxles formed at the lower end of one segment and a pair of trunnionrecesses formed at a corresponding location on the other segment, atleast the first, inboard, segment of the adapter having an effectiveweight sufficient to balance forces created by the pressure of a liquidcarried in the tube under centrifugation that act transversely to thecentral axis, so that, in use with the adapter inserted into a cavity ofa rotor with the mating surfaces of the adapter segments being incontacting relationship with each other, the effective weight of theinboard segment while under centrifugation is sufficient to maintain themating surfaces of the adapter segments in such contacting relationship.2. An adapter for supporting a closed centrifuge tube within a cavity ofa vertical angle centrifuge rotor, the adapter comprising:a first,inboard, adapter segment and a second, outboard, adapter segment, eachsegment having an exterior surface and a mating surface thereon, eachsegment having an indentation in the mating surface thereof, theindentation in each segment being shaped such that when the segments arejoined along their mating surfaces the indentations cooperate to definea recess able to totally surround a centrifuge tube disposed therein,the adapter having a central axis extending therethrough, at least onehinge connecting the segments and supporting the relative pivotalmovement, about a hinge axis, of at least one segment with respect tothe other from an open to a mated position, the hinge axis extendingperpendicular to the axis of the adapter, the hinge comprising a pair ofaxles formed at the lower end of one segment and a pair of trunnionrecesses formed at a corresponding location on the other segment, thesegments being fabricated of a material that has sufficient strength towithstand the vertical forces created by the pressure of a liquid undercentrifugation, at least the first, inboard, segment of the adapterhaving an effective weight sufficient to balance forces created by thepressure of a liquid carried in the tube under centrifugation that acttransversely to the central axis, so that, in use with the adapterinserted into a cavity of a rotor with the mating surfaces of theadapter segments being in contacting relationship with each other, theeffective weight of the inboard segment while under centrifugation issufficient to maintain the mating surfaces of the adapter segments insuch contacting relationship.
 3. An adapter for supporting a closedcentrifuge tube within a cavity of a centrifuge rotor, the adaptercomprising:a first, inboard, adapter segment and a second, outboard,adapter segment, each segment having an exterior surface and a matingsurface thereon, each segment having an indentation in the matingsurface thereof, the indentation in each segment being shaped such thatwhen the segments are joined along their mating surfaces theindentations cooperate to define a recess able to totally surround acentrifuge tube disposed therein, the adapter having a central axisextending therethrough, the inboard segment having a flange and theoutboard segment having a channel therein sized to receive the flange,the flange having serrations thereon, at least the first, inboard,segment of the adapter having an effective weight sufficient to balanceforces created by the pressure of a liquid carried in the tube undercentrifugation that act transversely to the central axis, so that, inuse with the adapter inserted into a cavity of a rotor with the matingsurfaces of the adapter segments being in contacting relationship witheach other, the effective weight of the inboard segment while undercentrifugation is sufficient to maintain the mating surfaces of theadapter segments in such contacting relationship.
 4. The adapter ofclaim 3 wherein the flange on the inboard segment has overhangingprojection thereon adapted to seat against a shelf provided in acentrifuge rotor.